Update the testing documentation to include the trybots.
Update the testing documentation to include the trybots.

BUG=504872

Change-Id: I9cbbe92afc9df6a4cb8f3ddf0c547492c6765c8e
Reviewed-on: https://chromium-review.googlesource.com/310011
Reviewed-by: Jamie Madill <7e492b4f1c8458024932de3ba475cbf015424c30@chromium.org>
Tested-by: Geoff Lang <b6fc25fe0362055230985c05cbfa8adb741ccc0f@chromium.org>

mlfarrell/angle,ecoal95/angle,ecoal95/angle,mlfarrell/angle,ecoal95/angle,domokit/waterfall,ppy/angle,ecoal95/angle,ppy/angle,mikolalysenko/angle,domokit/waterfall,mikolalysenko/angle,mlfarrell/angle,mlfarrell/angle,mikolalysenko/angle,ppy/angle,MSOpenTech/angle,ppy/angle,mikolalysenko/angle,MSOpenTech/angle,MSOpenTech/angle,ecoal95/angle,MSOpenTech/angle